Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1047 insertions, 0 deletions

diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
new file mode 100644
index 0000000000..ee71376f17
--- /dev/null
+++ b/drivers/char/hpet.c
@@ -0,0 +1,1047 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Intel & MS High Precision Event Timer Implementation.
+ *
+ * Copyright (C) 2003 Intel Corporation
+ *	Venki Pallipadi
+ * (c) Copyright 2004 Hewlett-Packard Development Company, L.P.
+ *	Bob Picco <robert.picco@hp.com>
+ */
+
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/miscdevice.h>
+#include <linux/major.h>
+#include <linux/ioport.h>
+#include <linux/fcntl.h>
+#include <linux/init.h>
+#include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/poll.h>
+#include <linux/mm.h>
+#include <linux/proc_fs.h>
+#include <linux/spinlock.h>
+#include <linux/sysctl.h>
+#include <linux/wait.h>
+#include <linux/sched/signal.h>
+#include <linux/bcd.h>
+#include <linux/seq_file.h>
+#include <linux/bitops.h>
+#include <linux/compat.h>
+#include <linux/clocksource.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/acpi.h>
+#include <linux/hpet.h>
+#include <asm/current.h>
+#include <asm/irq.h>
+#include <asm/div64.h>
+
+/*
+ * The High Precision Event Timer driver.
+ * This driver is closely modelled after the rtc.c driver.
+ * See HPET spec revision 1.
+ */
+#define	HPET_USER_FREQ	(64)
+#define	HPET_DRIFT	(500)
+
+#define HPET_RANGE_SIZE		1024	/* from HPET spec */
+
+
+/* WARNING -- don't get confused.  These macros are never used
+ * to write the (single) counter, and rarely to read it.
+ * They're badly named; to fix, someday.
+ */
+#if BITS_PER_LONG == 64
+#define	write_counter(V, MC)	writeq(V, MC)
+#define	read_counter(MC)	readq(MC)
+#else
+#define	write_counter(V, MC)	writel(V, MC)
+#define	read_counter(MC)	readl(MC)
+#endif
+
+static DEFINE_MUTEX(hpet_mutex); /* replaces BKL */
+static u32 hpet_nhpet, hpet_max_freq = HPET_USER_FREQ;
+
+/* This clocksource driver currently only works on ia64 */
+#ifdef CONFIG_IA64
+static void __iomem *hpet_mctr;
+
+static u64 read_hpet(struct clocksource *cs)
+{
+	return (u64)read_counter((void __iomem *)hpet_mctr);
+}
+
+static struct clocksource clocksource_hpet = {
+	.name		= "hpet",
+	.rating		= 250,
+	.read		= read_hpet,
+	.mask		= CLOCKSOURCE_MASK(64),
+	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+static struct clocksource *hpet_clocksource;
+#endif
+
+/* A lock for concurrent access by app and isr hpet activity. */
+static DEFINE_SPINLOCK(hpet_lock);
+
+#define	HPET_DEV_NAME	(7)
+
+struct hpet_dev {
+	struct hpets *hd_hpets;
+	struct hpet __iomem *hd_hpet;
+	struct hpet_timer __iomem *hd_timer;
+	unsigned long hd_ireqfreq;
+	unsigned long hd_irqdata;
+	wait_queue_head_t hd_waitqueue;
+	struct fasync_struct *hd_async_queue;
+	unsigned int hd_flags;
+	unsigned int hd_irq;
+	unsigned int hd_hdwirq;
+	char hd_name[HPET_DEV_NAME];
+};
+
+struct hpets {
+	struct hpets *hp_next;
+	struct hpet __iomem *hp_hpet;
+	unsigned long hp_hpet_phys;
+	struct clocksource *hp_clocksource;
+	unsigned long long hp_tick_freq;
+	unsigned long hp_delta;
+	unsigned int hp_ntimer;
+	unsigned int hp_which;
+	struct hpet_dev hp_dev[];
+};
+
+static struct hpets *hpets;
+
+#define	HPET_OPEN		0x0001
+#define	HPET_IE			0x0002	/* interrupt enabled */
+#define	HPET_PERIODIC		0x0004
+#define	HPET_SHARED_IRQ		0x0008
+
+static irqreturn_t hpet_interrupt(int irq, void *data)
+{
+	struct hpet_dev *devp;
+	unsigned long isr;
+
+	devp = data;
+	isr = 1 << (devp - devp->hd_hpets->hp_dev);
+
+	if ((devp->hd_flags & HPET_SHARED_IRQ) &&
+	    !(isr & readl(&devp->hd_hpet->hpet_isr)))
+		return IRQ_NONE;
+
+	spin_lock(&hpet_lock);
+	devp->hd_irqdata++;
+
+	/*
+	 * For non-periodic timers, increment the accumulator.
+	 * This has the effect of treating non-periodic like periodic.
+	 */
+	if ((devp->hd_flags & (HPET_IE | HPET_PERIODIC)) == HPET_IE) {
+		unsigned long t, mc, base, k;
+		struct hpet __iomem *hpet = devp->hd_hpet;
+		struct hpets *hpetp = devp->hd_hpets;
+
+		t = devp->hd_ireqfreq;
+		read_counter(&devp->hd_timer->hpet_compare);
+		mc = read_counter(&hpet->hpet_mc);
+		/* The time for the next interrupt would logically be t + m,
+		 * however, if we are very unlucky and the interrupt is delayed
+		 * for longer than t then we will completely miss the next
+		 * interrupt if we set t + m and an application will hang.
+		 * Therefore we need to make a more complex computation assuming
+		 * that there exists a k for which the following is true:
+		 * k * t + base < mc + delta
+		 * (k + 1) * t + base > mc + delta
+		 * where t is the interval in hpet ticks for the given freq,
+		 * base is the theoretical start value 0 < base < t,
+		 * mc is the main counter value at the time of the interrupt,
+		 * delta is the time it takes to write the a value to the
+		 * comparator.
+		 * k may then be computed as (mc - base + delta) / t .
+		 */
+		base = mc % t;
+		k = (mc - base + hpetp->hp_delta) / t;
+		write_counter(t * (k + 1) + base,
+			      &devp->hd_timer->hpet_compare);
+	}
+
+	if (devp->hd_flags & HPET_SHARED_IRQ)
+		writel(isr, &devp->hd_hpet->hpet_isr);
+	spin_unlock(&hpet_lock);
+
+	wake_up_interruptible(&devp->hd_waitqueue);
+
+	kill_fasync(&devp->hd_async_queue, SIGIO, POLL_IN);
+
+	return IRQ_HANDLED;
+}
+
+static void hpet_timer_set_irq(struct hpet_dev *devp)
+{
+	unsigned long v;
+	int irq, gsi;
+	struct hpet_timer __iomem *timer;
+
+	spin_lock_irq(&hpet_lock);
+	if (devp->hd_hdwirq) {
+		spin_unlock_irq(&hpet_lock);
+		return;
+	}
+
+	timer = devp->hd_timer;
+
+	/* we prefer level triggered mode */
+	v = readl(&timer->hpet_config);
+	if (!(v & Tn_INT_TYPE_CNF_MASK)) {
+		v |= Tn_INT_TYPE_CNF_MASK;
+		writel(v, &timer->hpet_config);
+	}
+	spin_unlock_irq(&hpet_lock);
+
+	v = (readq(&timer->hpet_config) & Tn_INT_ROUTE_CAP_MASK) >>
+				 Tn_INT_ROUTE_CAP_SHIFT;
+
+	/*
+	 * In PIC mode, skip IRQ0-4, IRQ6-9, IRQ12-15 which is always used by
+	 * legacy device. In IO APIC mode, we skip all the legacy IRQS.
+	 */
+	if (acpi_irq_model == ACPI_IRQ_MODEL_PIC)
+		v &= ~0xf3df;
+	else
+		v &= ~0xffff;
+
+	for_each_set_bit(irq, &v, HPET_MAX_IRQ) {
+		if (irq >= nr_irqs) {
+			irq = HPET_MAX_IRQ;
+			break;
+		}
+
+		gsi = acpi_register_gsi(NULL, irq, ACPI_LEVEL_SENSITIVE,
+					ACPI_ACTIVE_LOW);
+		if (gsi > 0)
+			break;
+
+		/* FIXME: Setup interrupt source table */
+	}
+
+	if (irq < HPET_MAX_IRQ) {
+		spin_lock_irq(&hpet_lock);
+		v = readl(&timer->hpet_config);
+		v |= irq << Tn_INT_ROUTE_CNF_SHIFT;
+		writel(v, &timer->hpet_config);
+		devp->hd_hdwirq = gsi;
+		spin_unlock_irq(&hpet_lock);
+	}
+	return;
+}
+
+static int hpet_open(struct inode *inode, struct file *file)
+{
+	struct hpet_dev *devp;
+	struct hpets *hpetp;
+	int i;
+
+	if (file->f_mode & FMODE_WRITE)
+		return -EINVAL;
+
+	mutex_lock(&hpet_mutex);
+	spin_lock_irq(&hpet_lock);
+
+	for (devp = NULL, hpetp = hpets; hpetp && !devp; hpetp = hpetp->hp_next)
+		for (i = 0; i < hpetp->hp_ntimer; i++)
+			if (hpetp->hp_dev[i].hd_flags & HPET_OPEN) {
+				continue;
+			} else {
+				devp = &hpetp->hp_dev[i];
+				break;
+			}
+
+	if (!devp) {
+		spin_unlock_irq(&hpet_lock);
+		mutex_unlock(&hpet_mutex);
+		return -EBUSY;
+	}
+
+	file->private_data = devp;
+	devp->hd_irqdata = 0;
+	devp->hd_flags |= HPET_OPEN;
+	spin_unlock_irq(&hpet_lock);
+	mutex_unlock(&hpet_mutex);
+
+	hpet_timer_set_irq(devp);
+
+	return 0;
+}
+
+static ssize_t
+hpet_read(struct file *file, char __user *buf, size_t count, loff_t * ppos)
+{
+	DECLARE_WAITQUEUE(wait, current);
+	unsigned long data;
+	ssize_t retval;
+	struct hpet_dev *devp;
+
+	devp = file->private_data;
+	if (!devp->hd_ireqfreq)
+		return -EIO;
+
+	if (count < sizeof(unsigned long))
+		return -EINVAL;
+
+	add_wait_queue(&devp->hd_waitqueue, &wait);
+
+	for ( ; ; ) {
+		set_current_state(TASK_INTERRUPTIBLE);
+
+		spin_lock_irq(&hpet_lock);
+		data = devp->hd_irqdata;
+		devp->hd_irqdata = 0;
+		spin_unlock_irq(&hpet_lock);
+
+		if (data) {
+			break;
+		} else if (file->f_flags & O_NONBLOCK) {
+			retval = -EAGAIN;
+			goto out;
+		} else if (signal_pending(current)) {
+			retval = -ERESTARTSYS;
+			goto out;
+		}
+		schedule();
+	}
+
+	retval = put_user(data, (unsigned long __user *)buf);
+	if (!retval)
+		retval = sizeof(unsigned long);
+out:
+	__set_current_state(TASK_RUNNING);
+	remove_wait_queue(&devp->hd_waitqueue, &wait);
+
+	return retval;
+}
+
+static __poll_t hpet_poll(struct file *file, poll_table * wait)
+{
+	unsigned long v;
+	struct hpet_dev *devp;
+
+	devp = file->private_data;
+
+	if (!devp->hd_ireqfreq)
+		return 0;
+
+	poll_wait(file, &devp->hd_waitqueue, wait);
+
+	spin_lock_irq(&hpet_lock);
+	v = devp->hd_irqdata;
+	spin_unlock_irq(&hpet_lock);
+
+	if (v != 0)
+		return EPOLLIN | EPOLLRDNORM;
+
+	return 0;
+}
+
+#ifdef CONFIG_HPET_MMAP
+#ifdef CONFIG_HPET_MMAP_DEFAULT
+static int hpet_mmap_enabled = 1;
+#else
+static int hpet_mmap_enabled = 0;
+#endif
+
+static __init int hpet_mmap_enable(char *str)
+{
+	get_option(&str, &hpet_mmap_enabled);
+	pr_info("HPET mmap %s\n", hpet_mmap_enabled ? "enabled" : "disabled");
+	return 1;
+}
+__setup("hpet_mmap=", hpet_mmap_enable);
+
+static int hpet_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct hpet_dev *devp;
+	unsigned long addr;
+
+	if (!hpet_mmap_enabled)
+		return -EACCES;
+
+	devp = file->private_data;
+	addr = devp->hd_hpets->hp_hpet_phys;
+
+	if (addr & (PAGE_SIZE - 1))
+		return -ENOSYS;
+
+	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+	return vm_iomap_memory(vma, addr, PAGE_SIZE);
+}
+#else
+static int hpet_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	return -ENOSYS;
+}
+#endif
+
+static int hpet_fasync(int fd, struct file *file, int on)
+{
+	struct hpet_dev *devp;
+
+	devp = file->private_data;
+
+	if (fasync_helper(fd, file, on, &devp->hd_async_queue) >= 0)
+		return 0;
+	else
+		return -EIO;
+}
+
+static int hpet_release(struct inode *inode, struct file *file)
+{
+	struct hpet_dev *devp;
+	struct hpet_timer __iomem *timer;
+	int irq = 0;
+
+	devp = file->private_data;
+	timer = devp->hd_timer;
+
+	spin_lock_irq(&hpet_lock);
+
+	writeq((readq(&timer->hpet_config) & ~Tn_INT_ENB_CNF_MASK),
+	       &timer->hpet_config);
+
+	irq = devp->hd_irq;
+	devp->hd_irq = 0;
+
+	devp->hd_ireqfreq = 0;
+
+	if (devp->hd_flags & HPET_PERIODIC
+	    && readq(&timer->hpet_config) & Tn_TYPE_CNF_MASK) {
+		unsigned long v;
+
+		v = readq(&timer->hpet_config);
+		v ^= Tn_TYPE_CNF_MASK;
+		writeq(v, &timer->hpet_config);
+	}
+
+	devp->hd_flags &= ~(HPET_OPEN | HPET_IE | HPET_PERIODIC);
+	spin_unlock_irq(&hpet_lock);
+
+	if (irq)
+		free_irq(irq, devp);
+
+	file->private_data = NULL;
+	return 0;
+}
+
+static int hpet_ioctl_ieon(struct hpet_dev *devp)
+{
+	struct hpet_timer __iomem *timer;
+	struct hpet __iomem *hpet;
+	struct hpets *hpetp;
+	int irq;
+	unsigned long g, v, t, m;
+	unsigned long flags, isr;
+
+	timer = devp->hd_timer;
+	hpet = devp->hd_hpet;
+	hpetp = devp->hd_hpets;
+
+	if (!devp->hd_ireqfreq)
+		return -EIO;
+
+	spin_lock_irq(&hpet_lock);
+
+	if (devp->hd_flags & HPET_IE) {
+		spin_unlock_irq(&hpet_lock);
+		return -EBUSY;
+	}
+
+	devp->hd_flags |= HPET_IE;
+
+	if (readl(&timer->hpet_config) & Tn_INT_TYPE_CNF_MASK)
+		devp->hd_flags |= HPET_SHARED_IRQ;
+	spin_unlock_irq(&hpet_lock);
+
+	irq = devp->hd_hdwirq;
+
+	if (irq) {
+		unsigned long irq_flags;
+
+		if (devp->hd_flags & HPET_SHARED_IRQ) {
+			/*
+			 * To prevent the interrupt handler from seeing an
+			 * unwanted interrupt status bit, program the timer
+			 * so that it will not fire in the near future ...
+			 */
+			writel(readl(&timer->hpet_config) & ~Tn_TYPE_CNF_MASK,
+			       &timer->hpet_config);
+			write_counter(read_counter(&hpet->hpet_mc),
+				      &timer->hpet_compare);
+			/* ... and clear any left-over status. */
+			isr = 1 << (devp - devp->hd_hpets->hp_dev);
+			writel(isr, &hpet->hpet_isr);
+		}
+
+		sprintf(devp->hd_name, "hpet%d", (int)(devp - hpetp->hp_dev));
+		irq_flags = devp->hd_flags & HPET_SHARED_IRQ ? IRQF_SHARED : 0;
+		if (request_irq(irq, hpet_interrupt, irq_flags,
+				devp->hd_name, (void *)devp)) {
+			printk(KERN_ERR "hpet: IRQ %d is not free\n", irq);
+			irq = 0;
+		}
+	}
+
+	if (irq == 0) {
+		spin_lock_irq(&hpet_lock);
+		devp->hd_flags ^= HPET_IE;
+		spin_unlock_irq(&hpet_lock);
+		return -EIO;
+	}
+
+	devp->hd_irq = irq;
+	t = devp->hd_ireqfreq;
+	v = readq(&timer->hpet_config);
+
+	/* 64-bit comparators are not yet supported through the ioctls,
+	 * so force this into 32-bit mode if it supports both modes
+	 */
+	g = v | Tn_32MODE_CNF_MASK | Tn_INT_ENB_CNF_MASK;
+
+	if (devp->hd_flags & HPET_PERIODIC) {
+		g |= Tn_TYPE_CNF_MASK;
+		v |= Tn_TYPE_CNF_MASK | Tn_VAL_SET_CNF_MASK;
+		writeq(v, &timer->hpet_config);
+		local_irq_save(flags);
+
+		/*
+		 * NOTE: First we modify the hidden accumulator
+		 * register supported by periodic-capable comparators.
+		 * We never want to modify the (single) counter; that
+		 * would affect all the comparators. The value written
+		 * is the counter value when the first interrupt is due.
+		 */
+		m = read_counter(&hpet->hpet_mc);
+		write_counter(t + m + hpetp->hp_delta, &timer->hpet_compare);
+		/*
+		 * Then we modify the comparator, indicating the period
+		 * for subsequent interrupt.
+		 */
+		write_counter(t, &timer->hpet_compare);
+	} else {
+		local_irq_save(flags);
+		m = read_counter(&hpet->hpet_mc);
+		write_counter(t + m + hpetp->hp_delta, &timer->hpet_compare);
+	}
+
+	if (devp->hd_flags & HPET_SHARED_IRQ) {
+		isr = 1 << (devp - devp->hd_hpets->hp_dev);
+		writel(isr, &hpet->hpet_isr);
+	}
+	writeq(g, &timer->hpet_config);
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+/* converts Hz to number of timer ticks */
+static inline unsigned long hpet_time_div(struct hpets *hpets,
+					  unsigned long dis)
+{
+	unsigned long long m;
+
+	m = hpets->hp_tick_freq + (dis >> 1);
+	return div64_ul(m, dis);
+}
+
+static int
+hpet_ioctl_common(struct hpet_dev *devp, unsigned int cmd, unsigned long arg,
+		  struct hpet_info *info)
+{
+	struct hpet_timer __iomem *timer;
+	struct hpets *hpetp;
+	int err;
+	unsigned long v;
+
+	switch (cmd) {
+	case HPET_IE_OFF:
+	case HPET_INFO:
+	case HPET_EPI:
+	case HPET_DPI:
+	case HPET_IRQFREQ:
+		timer = devp->hd_timer;
+		hpetp = devp->hd_hpets;
+		break;
+	case HPET_IE_ON:
+		return hpet_ioctl_ieon(devp);
+	default:
+		return -EINVAL;
+	}
+
+	err = 0;
+
+	switch (cmd) {
+	case HPET_IE_OFF:
+		if ((devp->hd_flags & HPET_IE) == 0)
+			break;
+		v = readq(&timer->hpet_config);
+		v &= ~Tn_INT_ENB_CNF_MASK;
+		writeq(v, &timer->hpet_config);
+		if (devp->hd_irq) {
+			free_irq(devp->hd_irq, devp);
+			devp->hd_irq = 0;
+		}
+		devp->hd_flags ^= HPET_IE;
+		break;
+	case HPET_INFO:
+		{
+			memset(info, 0, sizeof(*info));
+			if (devp->hd_ireqfreq)
+				info->hi_ireqfreq =
+					hpet_time_div(hpetp, devp->hd_ireqfreq);
+			info->hi_flags =
+			    readq(&timer->hpet_config) & Tn_PER_INT_CAP_MASK;
+			info->hi_hpet = hpetp->hp_which;
+			info->hi_timer = devp - hpetp->hp_dev;
+			break;
+		}
+	case HPET_EPI:
+		v = readq(&timer->hpet_config);
+		if ((v & Tn_PER_INT_CAP_MASK) == 0) {
+			err = -ENXIO;
+			break;
+		}
+		devp->hd_flags |= HPET_PERIODIC;
+		break;
+	case HPET_DPI:
+		v = readq(&timer->hpet_config);
+		if ((v & Tn_PER_INT_CAP_MASK) == 0) {
+			err = -ENXIO;
+			break;
+		}
+		if (devp->hd_flags & HPET_PERIODIC &&
+		    readq(&timer->hpet_config) & Tn_TYPE_CNF_MASK) {
+			v = readq(&timer->hpet_config);
+			v ^= Tn_TYPE_CNF_MASK;
+			writeq(v, &timer->hpet_config);
+		}
+		devp->hd_flags &= ~HPET_PERIODIC;
+		break;
+	case HPET_IRQFREQ:
+		if ((arg > hpet_max_freq) &&
+		    !capable(CAP_SYS_RESOURCE)) {
+			err = -EACCES;
+			break;
+		}
+
+		if (!arg) {
+			err = -EINVAL;
+			break;
+		}
+
+		devp->hd_ireqfreq = hpet_time_div(hpetp, arg);
+	}
+
+	return err;
+}
+
+static long
+hpet_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct hpet_info info;
+	int err;
+
+	mutex_lock(&hpet_mutex);
+	err = hpet_ioctl_common(file->private_data, cmd, arg, &info);
+	mutex_unlock(&hpet_mutex);
+
+	if ((cmd == HPET_INFO) && !err &&
+	    (copy_to_user((void __user *)arg, &info, sizeof(info))))
+		err = -EFAULT;
+
+	return err;
+}
+
+#ifdef CONFIG_COMPAT
+struct compat_hpet_info {
+	compat_ulong_t hi_ireqfreq;	/* Hz */
+	compat_ulong_t hi_flags;	/* information */
+	unsigned short hi_hpet;
+	unsigned short hi_timer;
+};
+
+static long
+hpet_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct hpet_info info;
+	int err;
+
+	mutex_lock(&hpet_mutex);
+	err = hpet_ioctl_common(file->private_data, cmd, arg, &info);
+	mutex_unlock(&hpet_mutex);
+
+	if ((cmd == HPET_INFO) && !err) {
+		struct compat_hpet_info __user *u = compat_ptr(arg);
+		if (put_user(info.hi_ireqfreq, &u->hi_ireqfreq) ||
+		    put_user(info.hi_flags, &u->hi_flags) ||
+		    put_user(info.hi_hpet, &u->hi_hpet) ||
+		    put_user(info.hi_timer, &u->hi_timer))
+			err = -EFAULT;
+	}
+
+	return err;
+}
+#endif
+
+static const struct file_operations hpet_fops = {
+	.owner = THIS_MODULE,
+	.llseek = no_llseek,
+	.read = hpet_read,
+	.poll = hpet_poll,
+	.unlocked_ioctl = hpet_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl = hpet_compat_ioctl,
+#endif
+	.open = hpet_open,
+	.release = hpet_release,
+	.fasync = hpet_fasync,
+	.mmap = hpet_mmap,
+};
+
+static int hpet_is_known(struct hpet_data *hdp)
+{
+	struct hpets *hpetp;
+
+	for (hpetp = hpets; hpetp; hpetp = hpetp->hp_next)
+		if (hpetp->hp_hpet_phys == hdp->hd_phys_address)
+			return 1;
+
+	return 0;
+}
+
+static struct ctl_table hpet_table[] = {
+	{
+	 .procname = "max-user-freq",
+	 .data = &hpet_max_freq,
+	 .maxlen = sizeof(int),
+	 .mode = 0644,
+	 .proc_handler = proc_dointvec,
+	 },
+	{}
+};
+
+static struct ctl_table_header *sysctl_header;
+
+/*
+ * Adjustment for when arming the timer with
+ * initial conditions.  That is, main counter
+ * ticks expired before interrupts are enabled.
+ */
+#define	TICK_CALIBRATE	(1000UL)
+
+static unsigned long __hpet_calibrate(struct hpets *hpetp)
+{
+	struct hpet_timer __iomem *timer = NULL;
+	unsigned long t, m, count, i, flags, start;
+	struct hpet_dev *devp;
+	int j;
+	struct hpet __iomem *hpet;
+
+	for (j = 0, devp = hpetp->hp_dev; j < hpetp->hp_ntimer; j++, devp++)
+		if ((devp->hd_flags & HPET_OPEN) == 0) {
+			timer = devp->hd_timer;
+			break;
+		}
+
+	if (!timer)
+		return 0;
+
+	hpet = hpetp->hp_hpet;
+	t = read_counter(&timer->hpet_compare);
+
+	i = 0;
+	count = hpet_time_div(hpetp, TICK_CALIBRATE);
+
+	local_irq_save(flags);
+
+	start = read_counter(&hpet->hpet_mc);
+
+	do {
+		m = read_counter(&hpet->hpet_mc);
+		write_counter(t + m + hpetp->hp_delta, &timer->hpet_compare);
+	} while (i++, (m - start) < count);
+
+	local_irq_restore(flags);
+
+	return (m - start) / i;
+}
+
+static unsigned long hpet_calibrate(struct hpets *hpetp)
+{
+	unsigned long ret = ~0UL;
+	unsigned long tmp;
+
+	/*
+	 * Try to calibrate until return value becomes stable small value.
+	 * If SMI interruption occurs in calibration loop, the return value
+	 * will be big. This avoids its impact.
+	 */
+	for ( ; ; ) {
+		tmp = __hpet_calibrate(hpetp);
+		if (ret <= tmp)
+			break;
+		ret = tmp;
+	}
+
+	return ret;
+}
+
+int hpet_alloc(struct hpet_data *hdp)
+{
+	u64 cap, mcfg;
+	struct hpet_dev *devp;
+	u32 i, ntimer;
+	struct hpets *hpetp;
+	struct hpet __iomem *hpet;
+	static struct hpets *last;
+	unsigned long period;
+	unsigned long long temp;
+	u32 remainder;
+
+	/*
+	 * hpet_alloc can be called by platform dependent code.
+	 * If platform dependent code has allocated the hpet that
+	 * ACPI has also reported, then we catch it here.
+	 */
+	if (hpet_is_known(hdp)) {
+		printk(KERN_DEBUG "%s: duplicate HPET ignored\n",
+			__func__);
+		return 0;
+	}
+
+	hpetp = kzalloc(struct_size(hpetp, hp_dev, hdp->hd_nirqs),
+			GFP_KERNEL);
+
+	if (!hpetp)
+		return -ENOMEM;
+
+	hpetp->hp_which = hpet_nhpet++;
+	hpetp->hp_hpet = hdp->hd_address;
+	hpetp->hp_hpet_phys = hdp->hd_phys_address;
+
+	hpetp->hp_ntimer = hdp->hd_nirqs;
+
+	for (i = 0; i < hdp->hd_nirqs; i++)
+		hpetp->hp_dev[i].hd_hdwirq = hdp->hd_irq[i];
+
+	hpet = hpetp->hp_hpet;
+
+	cap = readq(&hpet->hpet_cap);
+
+	ntimer = ((cap & HPET_NUM_TIM_CAP_MASK) >> HPET_NUM_TIM_CAP_SHIFT) + 1;
+
+	if (hpetp->hp_ntimer != ntimer) {
+		printk(KERN_WARNING "hpet: number irqs doesn't agree"
+		       " with number of timers\n");
+		kfree(hpetp);
+		return -ENODEV;
+	}
+
+	if (last)
+		last->hp_next = hpetp;
+	else
+		hpets = hpetp;
+
+	last = hpetp;
+
+	period = (cap & HPET_COUNTER_CLK_PERIOD_MASK) >>
+		HPET_COUNTER_CLK_PERIOD_SHIFT; /* fs, 10^-15 */
+	temp = 1000000000000000uLL; /* 10^15 femtoseconds per second */
+	temp += period >> 1; /* round */
+	do_div(temp, period);
+	hpetp->hp_tick_freq = temp; /* ticks per second */
+
+	printk(KERN_INFO "hpet%d: at MMIO 0x%lx, IRQ%s",
+		hpetp->hp_which, hdp->hd_phys_address,
+		hpetp->hp_ntimer > 1 ? "s" : "");
+	for (i = 0; i < hpetp->hp_ntimer; i++)
+		printk(KERN_CONT "%s %d", i > 0 ? "," : "", hdp->hd_irq[i]);
+	printk(KERN_CONT "\n");
+
+	temp = hpetp->hp_tick_freq;
+	remainder = do_div(temp, 1000000);
+	printk(KERN_INFO
+		"hpet%u: %u comparators, %d-bit %u.%06u MHz counter\n",
+		hpetp->hp_which, hpetp->hp_ntimer,
+		cap & HPET_COUNTER_SIZE_MASK ? 64 : 32,
+		(unsigned) temp, remainder);
+
+	mcfg = readq(&hpet->hpet_config);
+	if ((mcfg & HPET_ENABLE_CNF_MASK) == 0) {
+		write_counter(0L, &hpet->hpet_mc);
+		mcfg |= HPET_ENABLE_CNF_MASK;
+		writeq(mcfg, &hpet->hpet_config);
+	}
+
+	for (i = 0, devp = hpetp->hp_dev; i < hpetp->hp_ntimer; i++, devp++) {
+		struct hpet_timer __iomem *timer;
+
+		timer = &hpet->hpet_timers[devp - hpetp->hp_dev];
+
+		devp->hd_hpets = hpetp;
+		devp->hd_hpet = hpet;
+		devp->hd_timer = timer;
+
+		/*
+		 * If the timer was reserved by platform code,
+		 * then make timer unavailable for opens.
+		 */
+		if (hdp->hd_state & (1 << i)) {
+			devp->hd_flags = HPET_OPEN;
+			continue;
+		}
+
+		init_waitqueue_head(&devp->hd_waitqueue);
+	}
+
+	hpetp->hp_delta = hpet_calibrate(hpetp);
+
+/* This clocksource driver currently only works on ia64 */
+#ifdef CONFIG_IA64
+	if (!hpet_clocksource) {
+		hpet_mctr = (void __iomem *)&hpetp->hp_hpet->hpet_mc;
+		clocksource_hpet.archdata.fsys_mmio = hpet_mctr;
+		clocksource_register_hz(&clocksource_hpet, hpetp->hp_tick_freq);
+		hpetp->hp_clocksource = &clocksource_hpet;
+		hpet_clocksource = &clocksource_hpet;
+	}
+#endif
+
+	return 0;
+}
+
+static acpi_status hpet_resources(struct acpi_resource *res, void *data)
+{
+	struct hpet_data *hdp;
+	acpi_status status;
+	struct acpi_resource_address64 addr;
+
+	hdp = data;
+
+	status = acpi_resource_to_address64(res, &addr);
+
+	if (ACPI_SUCCESS(status)) {
+		hdp->hd_phys_address = addr.address.minimum;
+		hdp->hd_address = ioremap(addr.address.minimum, addr.address.address_length);
+		if (!hdp->hd_address)
+			return AE_ERROR;
+
+		if (hpet_is_known(hdp)) {
+			iounmap(hdp->hd_address);
+			return AE_ALREADY_EXISTS;
+		}
+	} else if (res->type == ACPI_RESOURCE_TYPE_FIXED_MEMORY32) {
+		struct acpi_resource_fixed_memory32 *fixmem32;
+
+		fixmem32 = &res->data.fixed_memory32;
+
+		hdp->hd_phys_address = fixmem32->address;
+		hdp->hd_address = ioremap(fixmem32->address,
+						HPET_RANGE_SIZE);
+		if (!hdp->hd_address)
+			return AE_ERROR;
+
+		if (hpet_is_known(hdp)) {
+			iounmap(hdp->hd_address);
+			return AE_ALREADY_EXISTS;
+		}
+	} else if (res->type == ACPI_RESOURCE_TYPE_EXTENDED_IRQ) {
+		struct acpi_resource_extended_irq *irqp;
+		int i, irq;
+
+		irqp = &res->data.extended_irq;
+
+		for (i = 0; i < irqp->interrupt_count; i++) {
+			if (hdp->hd_nirqs >= HPET_MAX_TIMERS)
+				break;
+
+			irq = acpi_register_gsi(NULL, irqp->interrupts[i],
+						irqp->triggering,
+						irqp->polarity);
+			if (irq < 0)
+				return AE_ERROR;
+
+			hdp->hd_irq[hdp->hd_nirqs] = irq;
+			hdp->hd_nirqs++;
+		}
+	}
+
+	return AE_OK;
+}
+
+static int hpet_acpi_add(struct acpi_device *device)
+{
+	acpi_status result;
+	struct hpet_data data;
+
+	memset(&data, 0, sizeof(data));
+
+	result =
+	    acpi_walk_resources(device->handle, METHOD_NAME__CRS,
+				hpet_resources, &data);
+
+	if (ACPI_FAILURE(result))
+		return -ENODEV;
+
+	if (!data.hd_address || !data.hd_nirqs) {
+		if (data.hd_address)
+			iounmap(data.hd_address);
+		printk("%s: no address or irqs in _CRS\n", __func__);
+		return -ENODEV;
+	}
+
+	return hpet_alloc(&data);
+}
+
+static const struct acpi_device_id hpet_device_ids[] = {
+	{"PNP0103", 0},
+	{"", 0},
+};
+
+static struct acpi_driver hpet_acpi_driver = {
+	.name = "hpet",
+	.ids = hpet_device_ids,
+	.ops = {
+		.add = hpet_acpi_add,
+		},
+};
+
+static struct miscdevice hpet_misc = { HPET_MINOR, "hpet", &hpet_fops };
+
+static int __init hpet_init(void)
+{
+	int result;
+
+	result = misc_register(&hpet_misc);
+	if (result < 0)
+		return -ENODEV;
+
+	sysctl_header = register_sysctl("dev/hpet", hpet_table);
+
+	result = acpi_bus_register_driver(&hpet_acpi_driver);
+	if (result < 0) {
+		if (sysctl_header)
+			unregister_sysctl_table(sysctl_header);
+		misc_deregister(&hpet_misc);
+		return result;
+	}
+
+	return 0;
+}
+device_initcall(hpet_init);
+
+/*
+MODULE_AUTHOR("Bob Picco <Robert.Picco@hp.com>");
+MODULE_LICENSE("GPL");
+*/